As a neophyte I was massively frustrated when, after a few moves, I was unable to enter any new notes. It took a long time before I realized that the PENCIL symbol was the one to use. Its label came up as DRAW. I do not connect drawing with note entering. Drawing is making shapes and lines.
It would be more useful if the key for entering notes was the note symbol and the existing NOTE symbol for instruments was replaced with the shape of an instrument.